Optical reference

Celestron NexStar 4SE: aperture, focal length and eyepiece fit

What the Celestron NexStar 4SE measures, the magnification and true field each eyepiece produces in it, and the barrel, mount payload and camera adapter that fit.

Published specifications

Aperture
102 mm (4.02 in)
Focal length
1325 mm
Focal ratio
f/13
Optical design
Maksutov-Cassegrain
Focuser / eyepiece barrel
1.25 in visual back
Mount
Computerized single-fork altazimuth (GoTo)
Highest useful magnification (published)
241x
Optical tube weight
5 lb

Eyepiece ladder

2 pairings

The 4SE is the only Maksutov in the SE line, a slow 102 mm f/13. The long 1325 mm focal length in a short tube gives crisp lunar and planetary detail, but the small aperture caps deep-sky reach.

Because magnification is the telescope's 1325 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 53x here and a 10 mm eyepiece gives 132x. The highest useful magnification is the published 241x, beyond which the image dims and softens without showing more detail.

The focuser takes 1.25 in eyepieces, so use 1.25 in eyepieces; a long low-power 2 in eyepiece will not fit this focuser.

Match an eyepiece, mount or camera